tighter bass

[crippledchicken]

i have my atlas 12 in a 142.5 L shiva box set at mid Q tuned between 20 and 21hz. if i want to tighten the bass a little more, should i shorten the vent a little and tune a little higher? i use for HT also i'm using a dual flare 4" precision port right now. thanks, crippledchicken

[GM]

Greets!

My definition of 'tighten' means to lower the sysQ, so tune it lower (longer vent). Raising sysQ (shorter vent) would be more 'slam', or 'punch'.

That said, BoxPlot predicts this cab is too big for this driver, so I would first either try damping the vent or reducing the Vb to ~100L to roll off the peaking at Fb.

GM

[crippledchicken]

Originally posted by GM
Greets!

My definition of 'tighten' means to lower the sysQ, so tune it lower (longer vent). Raising sysQ (shorter vent) would be more 'slam', or 'punch'.

That said, BoxPlot predicts this cab is too big for this driver, so I would first either try damping the vent or reducing the Vb to ~100L to roll off the peaking at Fb.

GM

hi there, when i run the driver in WINISD PRO, it calls for a little over 5 cu ft. for QB3 alignment is this program that far off? my actual internal volume is about 4.7 cu ft with 4" x14" vent. thanks, crippledchicken

[GM]

Greets!

WINISD isn't very accurate, don't know about the pro version. Anyway, I went searching to see if my specs were out of date and found I only had the low Q ones, my bad.

Which ones are you using, and for sure is it wired correctly?

GM

[crippledchicken]

Originally posted by GM
Greets!

WINISD isn't very accurate, don't know about the pro version. Anyway, I went searching to see if my specs were out of date and found I only had the low Q ones, my bad.

Which ones are you using, and for sure is it wired correctly?

GM

these are the paramaters i used http://www.ascendantaudio.com/archiv...-S%20specs.htm

[johninCR]

I'd suggest that before you change your box, put a variable pot instead of a resistor across that extra VC. That adjustability will help it be a better dual purpose sub. Then if you still need it "tighter" for music (which really depends on your tastes), stuff that port.

[crippledchicken]

Originally posted by johninCR
I'd suggest that before you change your box, put a variable pot instead of a resistor across that extra VC. That adjustability will help it be a better dual purpose sub. Then if you still need it "tighter" for music (which really depends on your tastes), stuff that port.

yeah, the pot is a good way to go i've been planing to get one just haven't done so yet. whats a good type pot to use for that? thanks

[GM]

Greets!

OK, then try damping the vent first and if you're not pleased, then lower tuning to 16-17Hz. I don't use flared vents and I know they need to be longer for a given Fb than the base tube diameter implies, but I get ~17.4 Hz for a 4" x 14" straight pipe and I'm surprised the flares would raise it that much.

Anyway, you're right, it needs a bigger cab, I would use ~5.4ft^3 tuned to 16-17Hz.

GM

[crippledchicken]

Originally posted by GM
Greets!

OK, then try damping the vent first and if you're not pleased, then lower tuning to 16-17Hz. I don't use flared vents and I know they need to be longer for a given Fb than the base tube diameter implies, but I get ~17.4 Hz for a 4" x 14" straight pipe and I'm surprised the flares would raise it that much.

Anyway, you're right, it needs a bigger cab, I would use ~5.4ft^3 tuned to 16-17Hz.

GM

thanks GM, you have been a great help. i think i need to try and save up some funds, and buy a little more accurate modeling program. cheers, crippledchicken

[GM]

Greets!

You're welcome, though we almost had a 'failure to communicate', and I'm really not 'with it' tonight, I didn't even think about changing the series resistor on the other VC.

Anyway, DW use to recommend a cheap 100 ohm, 5W pot from Digi-key, but they have a $25 min. billing IIRC, though if you have a 1 ohm resistor you can swap out, it will lower the Qts to ~0.384, yielding a similar roll off as the lower tuning.

GM